1. Field of the Invention
The present invention relates to a stock screening apparatus which is employed in the paper and pulp industries, and more particularly, to a stock screening apparatus in which a rotary shaft of a drum-shaped rotary body is disposed horizontally.
2. Description of the Related Art
Stock screening apparatus in which a fixed plate screen is disposed on a periphery of a rotor in such a manner as to be coaxial relative to the rotor is known (such apparatus being disclosed in, for example, Japanese Patent Laid-Open No. 164795/1989).
Since such stock screening apparatus has no mechanism for removing foreign materials on the upstream side of the rotor, foreign materials, such as stones or metals, may flow into a space between the rotor and the fixed plate screen, to thereby cause damaging of the rotor or the fixed plate screen and clogging of a part of the openings of the fixed plate screen. These greatly reduce the performance of the stock screening apparatus.
It has accordingly been proposed to provide a screening member upstream of the rotor and an impeller adjacent to the screening member. However, such provision increases the overall size of the equipment.
Also, in the stock screening apparatus of the above-described type, since the rotary shaft of the rotor is disposed vertically and the rotor has a height larger than its diameter, when a large apparatus is to be cleaned, the rotor or the cover must be separated from the apparatus body using an elevator or the like, to make cleaning a troublesome task.